star magnitude
Absolute Magnitude- Absolute magnitude is the intrinsic brightness of a sar computed as if viewed from a distance of 10 parsers. Or in other terms, it is the true brightness of a star instead of the apparent brightness. From the perspective of someone on Earth, absolute magnitude would be almost impossible to conclude because most stars are arther than 10 parsecs away and the brightness would be less as the light from that star has traveled many light years to reach Earth.
Apparent Magnitude- Apparent magnitude is the apparent brightness of a star or celestial body from just looking at it from Earth without any atomosphere and is usually different from absolute magnitude of the star. From the perspective of someone on Earth, apparent magntude is reachable for many stars because from observing the night sky you see many stars that have various brightnesses. These different brightnesses are due to the actual brightness of the star or the distance the star is from Earth.
Luminosity- Luminosity is the amount of electomagnetic energy a celestial body radiates per unit of time or is also understood as the measurement of brightness. A star's luminosity is determined by its size and temperature which also helps determine what kind of star it is, such as a super giant which is cooler then most stars but is very bright. From a prospective on Earth, luminosity is the measure of brightness stars have while looking at them in the night sky. Finding the luminosity of a star this way would be extremley hard as you would have to find the distance to the star from Earth to determine its size, find its color, and then would combine its size and color to determine the type of star it's and conclude what temperature range it could have.